Why is my characters hand spinning in a circle?
This is a very common error/mistake in the animation part of the blender. I am pretty sure that you have a keyframe with a value like '24' right next to another keyframe with a value of '384' (or some values like that). The keyframes are so close to each other and so different, that when they are played, they make the hand move super fast that way.
To fix this, I would delete the keyframes and remake them with smaller values.